Streams need trees.
Research on local watersheds1 has shown that the percentage of forest cover for a watershed or subwatershed is directly related to water quality. Forest cover of at least 40% or greater in the entire watershed is generally necessary to attain High Quality or Cold Water designations, and 68% or greater in the entire watershed is needed for Exceptional Value designation. Of particular importance is the naturally vegetated portion of a stream’s floodplain that directly borders its banks. These streamside forests, or forested riparian buffers, need to remain intact in order to maintain the health of the stream. Some of the ecological functions of a riparian buffer include:
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- filtration of runoff pollution, including nitrates which create harmful algal blooms, and fecal coliform bacteria
- uptake and removal of pollutants in groundwater and soil
- habitat protection for wildlife such as native insects and the songbirds that rely on them
- shading considered important to the health of a natural stream – many of our native fish need cool water in order to thrive
- anchoring of stream banks against erosion
- stabilization of the floodway and floodplain
- floodwater mitigation
- food for stream macroinvertebrates, in the form of fallen leaves
A 50-foot buffer zone around a stream’s banks is the minimum width required to keep a stream’s banks from eroding and collapsing. A 100-foot to 300-foot zone is ideal for the stream’s ecology to function. These extremely important and sensitive zones of natural vegetation require protection in order to preserve stream health and water quality.
As part of our on-going Watershed Restoration Program, Green Valleys Association forms partnerships with businesses, schools, and organizations to help restore the riparian buffers to streams within five major watersheds of northern Chester County. Since 2010 we have helped to plant over 4,000 trees and shrubs along tributaries to the French, Pickering, and Valley Creeks. It is our hope that these formerly-bare stream banks will soon be covered with young, thriving, streamside forests. We continue to actively pursue opportunities to transform more stretches of stream into green, forested corridors.
Our Watershed Restoration Program is spirited by Plant One Million, a multi-state campaign to plant one million trees throughout the 13 counties in southeastern Pennsylvania, New Jersey and Delaware, with a goal to restore the regions tree canopy to 30 percent.
Some of our past partnerships:
• Tree Vitalize (funding)
• Open Lands Conservancy (partner)
• West Vincent Township (partner)
• Tredyffrin Township (partner)
• Sierra Club members (volunteers)
• Valley Forge National Historic Park (volunteers & partner)
• Valley Forge Trout Unlimited (volunteers & partner)
• Pauline Morton Foundation (funding)
• George and Miriam Martin Foundation (funding)
• Girl Scouts & Boy Scouts (volunteers)
• Owen J. Roberts High School (volunteers)
• Siemens Medical Service (volunteers)
• Cabrini College (volunteers)